1. Field of the Invention
The invention relates to a capacitance touch sensing device. More particularly, the invention relates to a capacitance touch sensing device that can inhibit a erroneous detection that a user has touched a door handle when rainwater has accumulated on the upper surface or the like of the door handle in a vehicle provided with a keyless entry system. The invention also relates to a door locking device. More particularly, the invention relates to a door locking device that can reliably lock or unlock a door even when there is ice or snow on the top surface of a door handle in a vehicle provided with a keyless entry system.
2. Description of the Related Art
In the following description, the terms upper, lower, front, and rear refer to directions with respect to a vehicle. A door handle according to related art in a vehicle provided with a keyless entry system will now be described with reference to drawings. FIG. 26 is a perspective view of an example of a door handle according to related art, in which a lock sensor electrode of a capacitance touch sensor is provided on an upper portion of a door handle. FIG. 27 is a perspective view of an example of another door handle according to related art, in which a lock sensor electrode is provided on a side portion of a door handle.
The number of vehicles with keyless entry systems whereby a door of an automobile can be locked and unlocked without using a key has increased in recent years. Keyless entry systems include an authenticating portion provided inside the vehicle, a portable device that is carried by a user, a capacitance touch sensor which is provided in a door, handle 100 (see FIG. 26) outside the vehicle and detects when a user touches the door handle, a locking portion that locks the door, and an unlocking portion that unlocks the door. Reference numeral 104 in FIG. 26 denotes a recessed portion formed in the door panel outer surface.
The capacitance touch sensor shown in FIG. 26 includes a lock sensor electrode 101, an unlock sensor electrode 103, a driving portion (not shown), and a detecting portion (also not shown). The driving portion drives the touch sensor. The detecting portion detects when a user touches (i.e., contacts) the door handle to lock the door based on a signal from the lock sensor electrode 101, as well as detects when the user has touched the door handle to unlock the door based on a signal from the unlock sensor electrode 103. The lock sensor electrode 101 is housed in an upper portion of the door handle 100. Alternatively, as shown in FIG. 27, the lock sensor electrode 102 is housed in a backside portion (i.e., the portion that faces outward away from the vehicle) of the door handle 106. Also, as shown in FIGS. 26 and 27, the unlock sensor electrode 103 is housed in a front-side portion (i.e., the portion that faces inward toward the vehicle) of a handle portion 105 of the door handle 100 or 106.
The operation of this system will now be described. First, an unlock operation will be described with reference to FIG. 26. When the user carrying the portable device approaches the vehicle, the authenticating portion communicates with the portable device to authenticate the user. If the authenticating portion recognizes the user as a legitimate user and the capacitance touch sensor detects when the user has touched the backside surface of the handle portion 105 when the user then grabs the handle portion 105 of the door handle 100, the unlocking portion unlocks the door.
Next, a lock operation when the lock sensor electrode 101 is provided on the upper portion of the door handle 100 will be described with reference to FIG. 26. When the user carrying the portable device gets out of the vehicle, the authenticating portion communicates with the portable device to authenticate the user. If the authenticating portion recognizes the user as a legitimate user and the capacitance touch sensor detects when the user has touched the upper surface of the door handle 100 after the user has closed the door, the locking portion locks the door.
Next, a lock operation when the lock sensor electrode 102 is provided on the front-side portion of the door handle 106 will be described with reference to FIG. 27. When the user carrying the portable device gets out of the vehicle, the authenticating portion communicates with the portable device to authenticate the user. If the authenticating portion recognizes the user as a legitimate user and the capacitance touch sensor detects when the user has touched the front-side surface of the door handle 106 after the user has closed the door, the locking portion locks the door.
In this way, the keyless entry system enables the user to lock and unlock the door simply by touching the door handle 100 or 106 without performing a key operation, thereby making it easier to lock and unlock the door.
However, the keyless entry system described above has the following problems. First, a problem that arises when the lock sensor electrode 101 is provided on the upper portion of the door handle 100 will be described with reference to FIG. 26. When it rains, rainwater may collect on the upper surface of the door handle 100 and that rainwater may freeze. If rainwater freezes on the upper surface of the door handle 100, it may prevent the user from being able to directly touch (contact) the upper portion of the door handle 100 so the locking portion is unable to lock the door.
Also, if rainwater collects on the upper surface of the door handle 100 as described above, the floating capacitance of the rainwater may increase the capacitance near the lock sensor electrode 101 and the detecting portion may erroneously detect the user touching the upper surface of the door handle 100. If this happens, the door may end up locking against the intention of the user, even though the user did not touch the door handle 100.
A door touch sensor described in Japanese Patent Application Publication No. 2005-139634 (JP-A-2005-139634) has a lock sensor electrode provided in an upper portion of a door handle and therefore may have the same problem as that of the structure shown in FIG. 26.
Next, a problem that arises when the lock sensor electrode 102 is provided on the side portion of the door handle 106 will be described with reference to FIG. 27. In this case, when the user closes the door, the locking portion may lock the door as a result of a finger or a handbag touching the front-side surface of the door handle 106 even if the user has no intention of locking the door.
A door touch sensor described in Japanese Patent Application Publication No. 2006-344554 (JP-A-2006-344554) has a lock sensor electrode provided on a front-side portion of a door handle and thus may have the same problem as that of the structure shown in FIG. 27.